Alpha-amylases are technically significant enzymes. The use of said amylases for washing and cleaning agents is well established in industry, and they may be found in modern, high-performance washing and cleaning agents. An alpha-amylase is an enzyme that catalyzes the hydrolysis of the inner α-(1-4) glycosidic bonds of the amylose, but not the cleavage of terminal or α-(1-6) glycosidic bonds. Alpha-amylases therefore represent a group of esterases (E.C. 3.2.1.1.). Alpha-amylases catalyze the cleavage of starch, glycogen and other oligo- and polysaccharides that have a α-(1-4) glycosidic bond. In this respect, alpha-amylases are active against starch residues in the laundry and catalyze the hydrolysis thereof (endohydrolysis). Alpha-amylases that have broad substrate spectra are used in particular when inhomogeneous raw materials or substrate mixtures need to be converted, i.e. for example in washing and cleaning agents, since dirt may consist of starch molecules and oligosaccharides having different structures. The alpha-amylases that are used in the washing or cleaning agents known from the prior art are usually of microbial origin and generally originate from bacteria or fungi, for example of the genera Bacillus, Pseudomonas, Acinetobacter, Micrococcus, Humicola, Trichoderma or Trichosporon. Alpha-amylases are usually produced in biotechnological processes known per se using suitable microorganisms, for example using transgenic expression hosts of the genus Bacillus or using filamentous fungi.
One particularly well-characterized alpha-amylase is an enzyme obtained from the alkalophilic Bacillus sp. strain TS-23, which hydrolyzes at least five types of starch (Lin et al., Biotechnol Appl Biochem, 28: 61-68, 1998). The alpha-amylase from Bacillus sp. strain TS-23 has a pH optimum of about 9, although it is stable over a wide pH range (i.e. from about 4.7 to about 10.8). Its optimal temperature is about 45° C., but the enzyme is also active at lower temperatures, for example from about 15 to about 20° C.
The U.S. Pat. Nos. 7,407,677 B2 and 8,852,912 B2 also disclose specific alpha-amylases and the fragments thereof for use in washing and cleaning agents.
Nevertheless, there is a need for (alpha) amylase variants that have altered biochemical properties and therefore provide improved performance in industrial applications.